Telephone system



aLGOODRun/i.

TELEPHONE SYSTEM. APPLICATION FILED SEPT- 14 l1917.

, mma me 8 192m,

I? /m/en/fof.' l l gsar OFFa-.

CHARLES L. GOODRUN, OE NEW YORK, N. Y., ASSIGNOR To WESTERN ELECTRIC v COMPANY, 1NOORPORATED, or NEW YORK, N. Y., a CORPORATION or NEW i YORK l instance.

TELEPHONE SYSTEM.

rateatea aan@ s, i920.

Application filed September 1e, 1917. Serial No. 191,364.

To all whom it may concern Be it known that I, CHARLES L. GOODRUM, a citizen of the United States, residing at New York, in the county of New York and clear, concise, and exact description.

This invention relates to telephone systems wherein connections between subscribers" lines are effected by automatic switchin" mechanism.

Vlore particularly it is concerned with certain improvements in' the arrangement and mode of operation of the selective switches employed in such a system.

In selector switches of the long and short step type the primary set of impulses operates to give the brush shaft a number of long steps to select a desired group of trunk terminals, and in the second or trunk hunt'- ing movei'nent of the switch the brush shaft takes a series of short steps to wipe its brushes over the terminals of the selected group in search of an idle trunk. Selective switches of this character have been constructed so as to use two sets of brushes, one set of which is designed to coperate with half of the groups of terminals, and thel other set to coperate with the remaining groups. The different groups Of trunk terminals are arranged in the switch with respect .to their numerical designation in .such a manner that the primary or directive seriesof impulses sent out by the calling subscriber serves to place the shaft with one or the other of said sets of brushes in operative relation to the particular group of trunks which have access through succeeding switches and apparatus to the group of lines containing the desired subscribers line. Obviously, the amount of primary motion given the brush shaft depends upon the number of impulses sent into the switch, and the particular set of brushes so positioned in operative relation to the selected dividing the group of trunk terminals is the set lthat is to be used in extending the connection through an idle trunk in such group. Since half of the terminal groups" are served by one brush set and the remaining half served by the other set, a convenient manner of roups is to arrange them in accordance w1th their numerical designation. That is, the odd digit groups are served by one set of brushes and the even d1g1t groups by the other set.

nasmuh. as both sets of brushes are carrled on t e same shaft and moved together underthe control of the same actuating mechanism, it is desirable that provision be made whereby the particular set of brushes taken for use, in the extension of a telephone connection through such switch, be electrically associated with the calling or lncoming line to the exclusion of the other brush set. As seen above the set of brushes to be u se'd is determined by the number of the primary impulses sent to the switch. ln other words the brush selection, as well as the group selection, depends upon whether the number of impulses in said series be odd or even.

The principal Object of the invention is an arrangement of the controlling circuits of the switch wherein the side-switch escapement magnet is capable of discriminating between an odd and an even number of impulses to effect a selection of either one or the other of the brush sets.

In the following description reference is made to the drawing forming a part of this specification, wherein the figure diagrammatically illustrates a portion of a telephone system employing a selector switch of the aforementioned character, and in which are embodied the features of the present invention.

Before going into a discussion of the circuit operations involved in making a connection, a brief description will be given of the general arrangement of the selector arts. The shaft 11 is provided with a Ouble ratchet member 12 having on one side'thereof a series of closely spaced ratchet teeth 13, and on the other side a series of more remotely spaced teeth 14. Securely fastened to the upper end of the shaft 11 are two sets of brushes 15, 16, 17 and 18, 19, 20. The trunk terminal bank is divided into two sections as shown in the figure the odd groups of trunks being placed in the upper section and the even groups appearing in the lower one. Brushes 15, 16 and 17 are designed to wipe over the terminals bof all odd groups, and brushes 18, 19 and 20 'over the terminals of all even groups. While only two groups and a ortion of another are shown to a section 1t is obvious that as many groups as desirable maybe provided. Fixed the shaft ,capable of a comparatively wi e range of motion. The secondary magnet 28, .which serves to impart to the shaft 11 a series of short lor trunk-hunting steps, is provided with an armature 29 pivoted at 30, and a pawl 31 arranged to engage the ratchet teeth 13. `.A pawl 32 normally rests in engage-v ment with ratchet teeth 13 to hold the shaft -1n whatever position it may be raised to by stepping. magnets 24 and 28. Said pawl is pivotally secured tothe amature 33 of reease magnet 34, and 'is withdrawn by thisma et when. energized, to allow the brush sha to restore to normal. The ratchet teeth 14 are so spaced `that one long step of laces the brushes15, 16 an 17 immediate y below `the iirst group of`terminals in the odd digit section, which, in -a 1 OOO-line system, is the first hundred roup.

` 'lzwo steps of the primary magnet e evate `of the brush shaft, if an od the shaft to position the brushes 18, 19 and 20 in operative relation to the yfirst group in the even digit section which group corresponds to the second hundre f steps are taken, brushes 15, 16 and 17 are placed just below the second group inthe odd section which is the thlrd hundred group. And likewise throughout the range number of impulses is. sent to ma et 24, brushes 15,- 16 and 17 will be move into operative relation to the corresponding group of terminals in the odd section of the bank, whereas if an even number is sent, brushes 18, 19 and 20 are positioned just below the corresponding group in the even section.

. A description will now be method of extending a connection from the subscribers substatlo'n, shown at the left of the figure, to any desired trunk group appearing 1n the terminal bank. of the selector switch. Upon the removal of the receiver at the substation, conventionally shown at 1, a circuit is completed to e'ect the operation of an idle finder or other preliminar switch. Such switch immediately positlons its brushes 2 and 3 upon the terminals 4 and 5 respectively of the calling line, thereby completing a circuit through to the selector switch. This circuit includes the line relay 6 and is traceable from free pole of battery, left-hand winding of relay 6, first position contact and side-switch wiper 7, finder contact of relay 6, winding of relay three 4 given of the i .lay 37 to the Afree pole of battery.

brush 3, terminal 5, over the loop of -siibstaright-han winding of relay 6 to ground. Relay 6 attracts its armature and establishes a circuit from ground, armature and front battery and ound. The -abovedescribed operations ta e place in a very short space of time, and without any eiort on thesubscribers part other than removing the receiver from its hookt The sending'dial 10 is now manipulated to transmit a series of impulses corresponding in number to the first di 't of the called partys telephone number. or example, we will assume this system to be. a 1,000-line system. In such a case only first-,selector switches are necessary, and with( the custo-` mary division of trunks on a decimal basis, each trunk oup at the selector connects with a partlcular hundred group of sub.-

s'cribers lines.` The function of the first set of impulses is then to operate the relay 6 a corresponding number of times, whereby through the agency of other mechanisms hereinafter to be considered, ,the sel/actor switch shaft is elevated to place 'one/ of its brush sets immediately below the desired group of trunk terminals.

Let it be assumed for the purpose of illustration that the nurnber of the desired .line has 5 as its first digit. The rela 6 having its above traced circuit inte pted five times, vibrates its armature correspondingly. At each retraction of its armature, a circuit is established for magnet 24 as follows:

ground, armature and back contact of relay 6, armature and front contact of relay 9, conductor 35, side-switch wiper 36 and its first position contact, windin of magnet 24, elay 9 is slowA to release and does not retract its armature to the free pole of battery.

between impulses. In response to the closure of this circuit, the magnet 24 elevates the shaft 11 five long steps, land brings the brushes 15, 16 and 17 to a position justbelow the third group of terminals in the odd section. This is the fifth hundred group, onl a portion being shown inthe drawing.

pon the first retraction of the armature of relay 6, a circuit is completed for thel slow release relay 37 from ground, armature and back contact of relay 6, armature and front contact of relay 9, windin of reelay 37 attracts its armature and closes a circuit for the escape magnet 38, traceable from ground, armature and contact of relay 37, first position contact and side-switch wiper 39,

conductor 40, winding of escape magnet 38,

to battery and ground. The escape magnet is designed so as to step" the side switch from the first to the second positions upon deenergization. At the cessation of the first taaaeoa or group selecting set. of impulses the line relay 6 maintains its armature attracted for a sufficient time to permit slow release relay 37 to retract its armature, and thereby interrupt the circuit of magnet 38.` The side `switch is thus moved into its second position where a circuit is completed for the secondary stepping magnet 28. This circuitl may be traced from the free pole of battery, winding of magnet 28, interrupter contacts 41,42, conductor 43, second position contact and side-switch wiper 44, contact and right-hand armature of escape magnet 38, to ground. The interruptor contacts 41 and 42 are arranged to be opened by the armature 29 each time magnet 28 is" energized. When the magnet 28.,energizes, and thereby interrupts its own circuit, pawl 31 is actuated to step brushes 15, 16 and 17 over the terminals of the selected group in search of an idle trunk. Idle trunks are those upon whose test terminal a ground potential exists.

Assume that the trunk 45,46-, 47 is the first idle trunk encountered in the group. When the test brush 15 steps onto the test terminal of this trunk a circuit is completed for the escape magnet 38, traceable from the grounded test conductor 45, brush 15, conductor 48, second position Contact and sideswitch wiper 39,conductor 40, wlndlng of escape magnet 38 to battery, and ground. Magnet 38 is designed to step the side switch from the second to the third positions upon its energization. As soon as the above traced .circuit is closed, the escape magnet energizes and the side switch goes into position'3, thereby opening the circuit of stepping magnet 28. and arresting the movement of brushes 15, 16 and 17 upon the termlnals of the idle trunk 45,46, 47. At the same time the calling line is extended by the sideswitch wipers 7 and 8 to conductors 49 and 50, line brushes 16 and 17, and -thence to the trunk conductors 46 and 47. In a manner similar to that just described, if any other odd series of impulses is sent to'the switch,-

brushes 15, 16 and 17 are moved into opera1 tive relation to the corresponding odd group of terminals, land subsequently electrically associated with the vcalling line. At the end of the conversation, the calling subscriber by hanging up his receiver causes a ground to be placed upon the test terminal of the trunk 45, 46, 47 in any suitable manner. A circuit isthen traceable from grounded trunk conductor 45, test wiper 15, conductor 48, third osition contact and side-switch wiper 51, ofinor'mal contacts 54, winding of release magnet 34, to battery and ground. Magnet 34 by attracting its armature with- -draws the holding pawl 32 from ratchet teeth 13to permit a restoration of the brush shaft to normal. At the same time it closes a locking circuit for itself at the sprlng contacts 52 and 53, which' circuit leads from free pole of battery, winding of magnet 34, ott-normal contacts 54, contacts 53 and 52, to ground.

We will now follow the operation of the switch when the subscriber at substation 1 wishes to place himself in communication with a subscriber whose line designation is a number having an even first digit,as for instance, the` digit 6. Such a line is represented at the Selector switch by the sixth hundred group of trunks, which is therefore, the third group in the lower or even di it section of the bank.

pon the callirig subscriber manipulating the sending dial 10 to transmit a series of six impulses, line relay 6 vibrates its armature as before and causes the magnet 24 to elevate shaft 11 six long steps. This time the brushes 18, 19 and 2() are positioned below the desired group of trunk terminals. Also the brush 21, hereinbefore referred to, is brought to rest upon one of the projections 22 of conducting strip 23, namely, the third projection from the bottom. Strip 23 is connected by conductor 55 to a contact lever 56, mounted on a friction pivot 57, and arranged to engage a grounded contact 58, when in the position shown in the' figure. Armature 29 of the secondary magnet' carries an upwardly extending pin 59 designed to engage lever 56 and tilt it up out of contact with 58 upon the first actuation of said armature. The friction of its pivoted support is suicient to hold the lever 56 in such position until the shaft is again restored to normal, at which time a finger 60 moves it back into engagement with grounded contact 58.

When the series of group selecting impulses ceases and relay 6 retains its armature attracted, slow release relay 37 denergizes and permits escape magnet 38 to pass the side switch from the first to the second positions in the. manner previously explained. A new circuit is thereupon immediately established for the escape magnet leading from free pole of battery, winding of magnet 38, side-switch wiper 61 and its secondv position contact, back contact and left-hand armature of magnet 38, conductor 62, brush 21, projection 22, conductor 55 to ground at lever 56 and contact 58. The escape magnet energizes and steps the side switch to position 3 before the secondary magnet has had time to operate. In position 3 of the side switch a circuit is again completed for the escape magnet as follows z' free pole of battery, vwinding of magnet 38, side-switch Vwiper 61 and its third position contact, to ground over the path above traced. By attracting its left-hand arma' ture, magnet 38 interrupts its own circuit and upon denergization p asses the side switch into the fourth positlon. A circuit is now; closed for stepiing magnet 28 leading frm 'free pole o battery, windln of magne 28, interruptor contacts 41 an 42 conductor 43, fourth position contact and side-switch. wiper 44, to ground at the `contact and right-hand armature of magnet 38. Stepping ma et 28 elevates the shaft step4 by step to trall the brushes 1,8, 19 and 20 over the trunk terminals of the selected group which as assumed Yis the sixth hundred, group, or the one containing the trunkJ 63, 64, 65. 1f upon stepping onto the termi-- nals of such trunk a ground is found, indicating the vsame to be idle, the following circuit is completed: grounded test con-i ductor 63, test brush 18, conductor 66, fourth position contact and side-switch wiper 39, conductor 40, winding of magnet 38 to free pole of batter The escape magnet by energizing steps t e side switch from the fourth to the fth positions, thus opening the 'circuit of the magnet 28 and brin 'ng the brushes to rest on the terminals o the idle trunk.

Side-switch wipers 7 and 8 extend the calling line over conductors 67 and 68, brushes 20 and 19, to trunk conductors 65 and 64. At the end of conversation a release circuit is closed by placing a ground on test trunk 63. Such circuit leads from grounded` trunkconductor 63, test brush 18 conductor 66, fifth position contact and side-switch wiper 51, to the winding of the release magnet 34 and vfree pole of battery over the path previously traced. l

Referring again to the conducting strip 23, it will be seen that the pro'ections 22 are so spaced relative to the lengt of a long step of the shaft 11 that an even number of steps alwaiys'places brush 21 in' contact with one of sai projections. However, if an odd V number :of steps are taken, brush 21 is brought to rest, at the end of the primary movement, midway between two of the projections 22. Thus if an odd number of impulses are sent no ground is placed on brush 21 at the end of the primary movement, and the` esca e magnet subsequently moves the side sw1tch into position 3 to thereby connect the odd digit brushes 15, 16 and 17 with the incoming line. But if an even number of impulses are sent, brush 21 is grounded at the end ofthe primary movement and the escape magnet subse uently passes the side switch to sition 5, t ereby v connecting the even digit rushes 18,'19 and 20 with the incoming hne.

What is claimed is:

1. In a telephone sistem, a selective switch having two sets o brushes, an' incoming line associated .with said brushes but normally disconnected therefrom, impulse mechamsm and .means for operatin the same to actuate said brushes, a multlposition auxiliary switch for controlling said associated with said sets f brushes but normally disconnected therefrom, impulse operating mechanism for simultaneously moving said brush sets over the terminal groups of their respective sections, a multiposltion auxiliary switch and operating means therefor to control said impulse mechanism, and meansV for variably positioning said auxiliary switch to connect said incoming line to one or another of said brush sets,

dependent upon the number of impulses recelved by sald mechanism. .l

3. In a telephone system, a switch having its terminal bankdivided into sections, a set of brushes for each section, a stepping magnet for moving said brush sets simultaneously over their respective sections. of the terminal bank, a circuit for the stepping magnet and means for sendin a series of impulses' over`said circuitxto operate the magnet, a switch for. controlling said circuit, and means for controlling the operation of such switch to render eectiveone or -another of said sets of brushes dependent Y upon the character of the impulse series sent to said stepping magnet.

4. In a telephone system, a switch havin a terminal bank composed of groups o terminals, a brush shaft having a plurality of brush sets fixed thereon, each set being arranged to coperate with a separate portion of the groups of said bank, an operating circuit having a Vstepping magnet therein for moving said shaft to position any one of said brush sets in operative relation to any terminal group served by such set, an auxiliary switch operative to control said operating circuit, and means for controlling the .oeration of said auxiliary switch to render e ective the particular set of brushes moved into operative position by the stepping magnet 5i In a telephone system, a line, a switch having a divided terminal bank, each division consisting of a plurality of roups of terminals, a plurality of sets o brushesv mounted on a common shaft, one set for each division of said tbank, a primary magnet and an impulse circuit therefor, means for causing a series of impulses to traverse said magnet to position one of said brush sets in operative relation to any group in the division served by such set, a secondary magnet and an impulse circuit therefor, means for causing a series of impulses to es 'for each section, an incoming hne.

les

ieaooe traverse the secondary magnet to move a positioned set of brushes over a group of acter of the impulse series traversing the primary magnet.

6. ln a telephone system, a line, a switch having a bank of terminal groups, a plurality of brush sets, each set assigned to a separate portion of the groups of said bank, a primary magnet and an impulse circuit therefor, means eective to produce a series of impulses in said circuit to cause said magnet to position a set of brushes in operative relation to any terminal group served by such set, a secondary magnet and an impulse circuit therefor, means for causing a series of impulses to traverse said secondary magnet to wipe a. positioned set of brushes over a group of terminals, a controlling switch for said impulse circuits with means to actuate the same through a series of successive positions, said switch being arranged to control the secondary mpulse circuit in a plurality ofsuch positions,

1 means controlling the actuation of the controlling switch to predetermine its controlling position dependent upon the number of impulses produced in said primary impulse circuit, and means for connecting said line to one or another of said setsof brushes dependent upon the position assumed by the controlling switch.

7. In a telephone system, a switch having a plurality of brush sets, a line, operating means for giving said brush sets a primary movement, operating means for giving said brush sets a secondary movement, an auxiliary switch with actuatingmeans therefor arranged to assume a plurality of diierent positions for controlling said secondary operating means, and means including the auxiliary switch for connecting said line to a particular one o said brush sets, dependent upon the controlling position assumed by said auxiliary switch.

8. in a telephone system, a selector switch I having a plurality of brushes, impulse Aoperated 'mechanism for actuating said brushes, and a multiposition side switch for controlling the impulse mechanism and also serving to render one or another of said brushes eective dependent upon the operation of said impulse mechanism, and in accordance with the position assumed by said side switch;

ln witness whereof, l hereunto subscribe my name this 8th day of September, A. D. 

